After not playing paintball for about 6 months, I broke out my MR2 to play next week. Charged it up, and it won't fire on burst or auto. If I recall, the color of the light should change but it's not doing that. It just stays semi auto no matter where I put the switch. On burst, it shoots semi. On auto, it stays on semi. Any suggestions as to why? It works on semi, but I intend to sell it soon and it needs to be functioning.